The reaction is catalysed in vivo in the opposite direction to that shown. A multifunctional enzyme that further reduces the product to the lignan (-)-secoisolariciresinol [EC 1.23.1.2, (+)-lariciresinol reductase]. Isolated from the plants Forsythia intermedia [1,2], Thuja plicata (western red cedar) [3], Linum perenne (perennial flax) [5] and Linum corymbulosum [6]. The 4-pro-R hydrogen of NADH is transferred to the 7-pro-R position of lariciresinol [1].